Shenandoah Valley Wastewater Treatment Plant Network PURE H2O FORUM Safeguarding Operations Personnel Understanding Arc Flash & Developing an Electrical Safety Program September 25, 2015 Presenter: Steve Bowman, PE Vice President Energy & MEP Group Leader sbowman@wileywilson.com
OBJECTIVES Why is Electrical Safety important and what is my responsibility? What is arc flash? What happens during an arc flash event? What is an arc flash analysis and does our organization need one?
OBJECTIVES What should we require in the way of deliverables? How do we modify our behavior after the analysis? Why have an Electrical Safety Program and will it help prevent injuries?
IMPORTANCE OF ELECTRICAL SAFETY What should we require in the way of deliverables? How do we modify our behavior after the analysis? Why have an Electrical Safety Program and will it help prevent injuries?
ELECTRICAL SAFETY STATISTICS Electrocution is the 4 th leading cause of death in the US industrial workplace 97% of electricians report having been shocked or injured on the job Long term effects of shocks on human health unknown 80% of electrical injuries are related to arc flash incidents
ELECTRICAL SAFETY STATISTICS 5-10 arc explosions occur in the United States every day 2000 people are treated in burn trauma units every year resulting from arc flash incidents Someone dies from an electrical event in the United States every working day (and that includes significant improvement over the last decade)
COST OF AN ARC FLASH INCIDENT $1.5M average cost of medical treatment 8-12 months away from work (on average) $10-12M average litigation cost for general industry incident Human tragedy
WHAT IS MY RESPONSIBILITY Position of Authority Set the tone for work practices Define the importance of safety
IMPORTANCE OF AN ELECTRICAL SAFETY PROGRAM The goal is to minimize risk Eliminate the hazard Substitute lower hazards for higher hazards Implement engineering controls to limit risk Raise awareness of risks and their consequences Establish administrative controls to regulate work practices Mandate the use of personal protective equipment (PPE) as a last resort
WHAT S INCLUDED IN AN ELECTRICAL SAFETY PROGRAM Definition of the hazards that exist Acknowledgement of situational realities Tool to assess the work required Process to request electrical outage Process to request energized work permit Lock-out/Tag-out (LO/TO) procedures Description of available PPE
ARC FLASH Regulatory Compliance OSHA effective August 2007, regulations require that employers protect employees against arc flash hazards Since 2002, NEC requires field marking of equipment requiring service while energized NFPA 70E industry standard for guidance on electrical safety in the workplace IEEE 1584 defines a standard for calculating incident energy levels
ARC FLASH NFPA Definition Electrical current that passes through air when insulation or isolation between electrified conductors is no longer sufficient to withstand the applied voltage
ARC FLASH Incident Energy The amount of energy impressed on a surface, a certain distance from the source, generated during an electrical arc event Often expressed in calories/cm 2, which aligns with ratings given to PPE Function of short circuit current and the length of time that the current is permitted to flow
ARC FLASH
PHYSICAL IMPACTS OF ARC FLASH 35,000 F Molten Metal Pressure Waves Hot Air-Rapid Expansion Sound Waves Shrapnel Copper Vapor Intense Light
NATURE OF A ELECTRICAL ARC Heat Temperature within the arc can be up to 35,000 F (4x hotter than surface of the sun) Fatal burns can occur several feet from arc Cotton clothing can ignite several feet from arc Non-cotton clothing can melt into the skin several feet from arc
PPE PERFORMANCE TEST
PERSONAL PROTECTIVE EQUIPMENT NFPA 70E, Table H.3(b) provides guidance Less than or equal to 1.2 calories/cm 2 Greater than 1.2 to 12 calories/cm 2 Greater than 12 calories/cm 2
NATURE OF A ELECTRICAL ARC Light Intense light can cause immediate and permanent eye damage Intense light can cause early development of cataracts
NATURE OF A ELECTRICAL ARC Hot Vapor Expansion Solid copper to copper vapor expands at a rate of 67,000/1 Water to vapor expands at a rate of 1670/1 Lung damage can readily occur
NATURE OF A ELECTRICAL ARC Molten Debris Droplets of molten metal may be propelled several feet and lodge in clothing or skin and then solidify again Blast shrapnel can penetrate the body with speeds in excess of 700 mph
NATURE OF A ELECTRICAL ARC Pressure and Sound Waves Blast pressure of up to 2000 lbs/ft 2 on a body Deafening explosion
NATURE OF A ELECTRICAL ARC Pressure and Sound Waves Blast pressure of up to 2000 lbs/ft 2 on a body Deafening explosion Case Study Will Tyree, Lynchburg Electrician
WHAT IS ARC FLASH ANALYSIS? Thorough and accurate data collection and system modeling Incident energy calculations Protective device coordination study Scope of the study should be limited only if administrative procedures are in place to restrict energized work Licensed professional engineer
PROTECTIVE DEVICE COORDINATION NEC Definition Localization of an overcurrent condition to restrict outages to the circuit or equipment affected, accomplished by the choice of overcurrent protective devices and their ratings or settings
ONE-LINE DIAGRAM
ONE-LINE DIAGRAM Fault Location X
EXISTING CONDITIONS
RECOMMENDED MODIFICATIONS
OVERCURRENT PROTECTIVE DEVICE COORDINATION Required by the NEC for Emergency Systems (Life Safety and Critical Branches) and for Legally Required Standby Systems (Equipment Branch) Case Study Fault in motor windings at hospital resulted in disruption of the critical branch for five hours
CORRELATION BETWEEN ARC FLASH HAZARD AND PROTECTIVE DEVICE COORDINATION System adjustments to improve coordination will sometimes have an adverse effect on incident energy
MITIGATION TECHNIQUES TO REDUCE INCIDENT ENERGY Make use of OCPD adjustments Replace basic OCPDs with more adjustable types Reconfigure the system More branches, smaller transformers Remove main devices to exterior of cabinets Maintenance mode on OCPDs Zone selective interlocking Optical sensors
ANALYSIS DELIVERABLES One-line diagrams for systems studied Medium-voltage distribution system Low-voltage building systems TCC coordination sheets Recommendations for coordination improvement Arc flash incident energy calculations Arc flash mitigation recommendations Arc flash hazard labels
ARC FLASH HAZARD LABELS Header Color: Orange for incident energy values <40 cal/cm 2 Red for values 40 cal/cm 2 and greater PPE required, qualified person or continuously escorted unqualified person No unqualified persons Calculated energy at specified working distance Voltage Insulation Class Reference to PPE Guidance in NFPA 70E, Annex H Considered equivalent to making contact with energized parts Calculation Date
FOLLOW-UP STEPS There is a cost of ownership associated with an Arc Flash Analysis NFPA 70E requires refreshing the study when a major modification or renovation takes place, not to exceed five years Requires engineer to update the study and provide new labels with each significant alteration
FOLLOW-UP STEPS How do we change behavior after an analysis? Development or Enhancement of Electrical Safety Program Energized Work If? When? Who has authority? PPE for energized work
WHAT S INCLUDED IN AN ELECTRICAL SAFETY PROGRAM? Definition of the hazards that exist Acknowledgement of situational realities Tool to assess the work required Process to request electrical outage Process to request energized work permit Lock-out/Tag-out (LO/TO) procedures Description of available PPE
HOW CAN I PROTECT MYSELF, CO-WORKERS, EMPLOYEES? DO NOT Work on Energized Equipment!!!
JUSTIFICATION FOR ENERGIZED WORK Work on energized electrical equipment is permitted when: Employer can demonstrate that deenergizing will create additional or greater hazards, or Employer can demonstrate that the task to be performed is infeasible in a de-energized state due to equipment design or operational limitations, or Energized conductors and parts operate at less than 50 volts, and there will be no increased exposure to electrical burns or arcs
INFEASIBLE VS. INCONVENIENT Infeasible Not practical; not capable of being done or carried out Inconvenient Inopportune; untimely; not suiting one s needs or purposes
IF ENERGIZED WORK IS NECESSARY Know and abide by the requirements set forth in the NFPA 70E, including: Obtain hot work permit (including justification) Be a qualified person Train, train, train! Use lock-out/tag-out procedures Follow your electrical safety program/procedures Know the hazard and the risks Wear your PPE!
QUALIFIED PERSON NFPA Definition One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved OSHA Definition Expands on the NFPA definition by expanding to say demonstrated skills
TRAINING Safety training Training on construction and operation on specific equipment First Responder / First Aid / CPR training Training must be documented
QUESTIONS Contact Information: Steve Bowman sbowman@wileywilson.com 434.455.3229 wileywilson.com